Numerical and experimental characterization of the single-use bioreactor Xcellerex™ XDR-200

Abstract

The optimization of operating conditions is vital for cell culture process development. In the present study, the pilot-scale single-use bioreactor Xcellerex™ XDR-200, which is typically used in cell culture scale-up, is investigated. This unbaffled reactor is equipped with an off-centered, bottom mounted impeller, and has a maximum working volume of 200 L. The flow field for this sparsely investigated bioreactor configuration is studied with computational fluid dynamics. Moreover, numerical simulations of the mixing time and the volumetric oxygen mass transfer coefficient for seven different test conditions are validated against experimental data. Mixing times across all tested conditions are found to remain below 30 s, and the volumetric oxygen mass transfer coefficient is between 2.0 and 20.0 h−1, which is a typical range for animal cell culture processes. These values of the oxygen transfer coefficient are found for as low as 0.004–0.125 L L−1 min−1 sparging rates with the microporous sparger. The hydrodynamic stress remains below critical values for cell damage for all conditions investigated. Vortex formation is suppressed in the bioreactor even though it is unbaffled due to off-centered impeller. Across the test conditions, the highest investigated impeller speed of 200 rpm is the most favorable due to fast mixing and high oxygen transfer.